abdominal luminal organs Flashcards
complex (imaging) investigation
- plain X-ray, incl. fluoroscopy
- Ultrasound
- CT
- MRI
- conventional nuclear medicine
- PET
- “hybrid imaging”
(+/- contrast)
GI contrast
- barium: insoluble, excellent contrast
- iodine (Gastrografin): water soluble, suspected leak/perforation
- single contrast: contours, stenosis, but may be fooled.
Good for functional studies - peristalsis - double contrast: barium coats mucosal surface, air dilates the lumen.
Better specificity and sensitivity
what to describe about an imaging exam
- what type of examination?
Is it contrast enhanced? IV or oral? What is the timing of enhancement?
Orientation (CT/MR) / probe (US) - what is being imaged?
- what is the significant finding?
- relevant negatives
- what is the differential diagnosis? (most likely first)
imaging recommendations for abdominal mass
CT or MRI of the abdomen, with IV contrast.
In some cases: ultrasound
imaging recommendations in blunt abdominal trauma
hemodynamically unstable pt: CXR, AXR, FAST scan
hemodinamically stable pt: CT of the abdomen & pelvis, with IV contrast
imaging recommendations for dysphagia
If the cause is known (eg. prior cancer or stroke) -> oropharyngeal motility study
If no known cause -> oropharyngeal motility and esophagography
imaging recommendations for inflammatory bowel disease (esp. Crohn disease)
CT of abdomen & pelvis, with IV contrast.
CT enterography.
MR enterography.
fluoroscopic small bowel series.
imaging recommendations for jaundice
ultrasound of abdomen
imaging recommendations for staging of GI cancer
CT scan of chest, abdomen, and pelvis, with IV contrast
imaging recommendations for suspected small bowel obstruction
CT of abdomen and pelvis, with IV contrast.
AXR
luminal digestive tract (anatomy)
- orophraynx
- esophagous
- stomach
- duodenum
- jejunum
- ileum
- colon
- rectum
- anal canal
oropharynx: anatomy, imaging, when to use
ANATOMY:
third part of pharynx. From soft palate to hyoid bone. Key event: swallowing
IMAGING:
Oropharyngeal motility study & fluoroscopic swallow of iodinated contrast
WHEN TO EXAMINE:
- elderly with recurrent pneumonia
- post stroke
- Head & Neck cancer
- aspiration (?)
esophagous: anatomy, imaging, when to use
ANATOMY:
from pharyngoesophageal junction (C5/C6) to Gastroesophageal junction.
Peristalsis: 5-9 seconds.
- primary (vagus), secondary (intrinsic), and tertiary waves.
IMAGING:
1) contrast swallow -> single or double contrast
* WHEN:
- as part of “upper GI study”
- after normal or impossible or perforated endoscopy
- motility disorders and reflux
2) CT, MRI, endoluminal US
* WHEN:
local staging of esophageal cancer
stomach: anatomy, imaging, when to use
ANATOMY:
cardia, fundus, body, antrum, pylorus
IMAGING:
1) contrast swallow -> single or double contrast (CO2 producing crystals)
* WHEN:
- as part of “upper GI study”
- after normal or impossible or perforated endoscopy
- motility disorders & reflux
2) CT
* WHEN:
cancer staging
duodenum: anatomy, imaging, when to use
ANATOMY:
- bulb, second, third, fourth parts (–> 90% peptic ulcers in the bulb)
- only partly intraperitoneal
- ampulla of Vater in the second part
- Ligaentum of Treitz marks boundary with jejunum
- Blood supply: celiac axis
IMAGING:
- endoscopy first
- single contrast swallow: after bariatri surgery - for anastomotic leak
- CT or MR to stage cancer
small bowel: anatomy
Ligamentum of Treitz to ileocecal valve.
7m long.
Mesentery: blood vessels, fat, nerves, lymph nodes. (classified as organ from 2016)
jejunum: proximal 40% -> thicker wall, wider lumen, more folds
ileum: distal 60%
Blood supply: SMA
small bowel: when to examine
- investigation of weight loss
- abdominal pain (after large bowel pathology excluded)
- follow up of surgery and IBD
- strictures, ulcers and dysmotility
small bowel: possible examinations
- single contrast “follow through”
- positive contrast & CT
- negative contrast & MR/CT
- positive contrast & fluoroscopy
- double contrast “enteroclysis”
- NJ tube (NasoJejunal), barium, methylcellulose chaser & fluoroscopy
- capsule endoscopy
- US: terminal ileum in IBD
large bowel: anatomy
1.5 m
caecum, appendix, ascending - transverse - descending - sigmoid colon, rectum, anal canal
arterial supply : SMA (jejunum to splenic flexure) , IMA (beyond)
large bowel: when to examine
- rectal bleeding
- anaemia
- abdominal pain
- weight loss
- colonoscopy: first line unless acute!
large bowel: imaging
1) CT colonoscopy (“virtual colonscopy”)
- bowel preparation, muscle relaxant, air or CO2 insufflation via rectal tube
- prone and supine CT series
- reconstructed “open” or “fly through”
2) double contrast barium enema
- selected cases only, excellent mucosal detail
3) single contrast enema
- postoperative, fistulas, level of obstruction, frail
4) CT & MR for staging cancer or acute abdomen (CECT)
5) US in appendicitis
basic patterns of pathology
- filling defect (in the lumen)
- mural
- extraluminal projections
- compression
- distension
- narrowing
filling defects
1) polyps
- benign or malignant
- sessile or pedunculated
- 1-2 cm
2) masses
- more often malignant (adenocarcinoma below lower esophagous)
- >2cm
- exophytic (into lumen) may bleed and obstruct early
- intramural spread (infiltrate the wall) cause annular constriction
intrinsic wall abnormality (mural)
- fold thickening
- inflammation: gastritis / colitis
- edema: heart failure, ischemia
- infiltration: lymphoma, linitis plastica
extraluminal projections
- ulcers - mucosal defect
- benign Vs malignant
- diverticula - mucosa intact
- true: all layers of the wall
- false: mucosa only (colonic)
the role of plain film in abdominal imaging
- erect CXR
- first line of investigation
- perforation
- position of NGT (nasogastric tube)
- AXR:
- may be helpful in obstruction
- mechanical obstruction Vs ileus
- level of pathology
BUT: CECT is the first line!
endoscopy
- gastroenterologist / surgeon
- directly visualise
- biopsy
- treat (inject / stent)
- invasive
- risk
- cost
radiology
- radiologist
- no need for sedation
- fewer complications
- better at small bowel evaluation
- may need endoscopy later
pathology of the esophagus
- neoplastic: SCC, adenocarcinoma -> mass or stricture
- congenital: atresia or TOF (tetralogy of Fallot)
- degenerative: achalasia -> classic beaking / diverticula -> classic pouching - by anatomical region
- inflammatory: reflux -> short stricture
- traumatic: ingestion of acid -> long stricture
- neurological: dysmotility -> “corkscrew esophagus”
- vascular: varicies -> smooth indentations
pathology of the stomach
- inflammatory: gastritis -> erosions & thickening / peptic ulcer disease -> ulcers
- neoplastic: adenocarcinoma -> mass
- iatrogenic: bariatric surgery -> distorted anatomy
pathology of the small bowel
- iatrogenic: adhesions -> obstruction
- inflammatory: Crohns -> ulcers & strictures – “string sign of Kantour”
- vascular: ischemia from SMA -> edema, pneumatosis
- infective: TB -> edema, obstruction
- neoplastic: lymphoma & adenocarcinoma (rare)
pathology of the large bowel
- neoplastic: adenocarcinoma -> mass, obstruction
- inflammatory: ulcerative colitis -> pseudopolyps, ulcers
- vascular: ischemia from SMA/IMA -> edema
- congenital: sigmoid volvulus -> obstruction
